Owing to the abundance and low cost of their precursors, along with their superior sodium storage capability, biomass-derived hard carbons hold great promise as anodes for sodium-ion batteries. However, how precursor molecular structure governs hard carbon properties remains unclear. Herein, corn starch is employed as a model system to compare linear amylose and highly branched amylopectin on crosslinking and hard carbon anodes. The abundant branch points and amorphous regions of amylopectin facilitate more thorough crosslinking with (NH₄)₂HPO₄, forming a denser three-dimensional network. In contrast, dense crystalline domains of amylose restrict crosslinker penetration. These differences dictate the microstructure of carbonized products: high-amylopectin derived hard carbon (A-HC) exhibits smaller interlayer spacing and higher graphitization, whereas high-amylose derived hard carbon (S-HC) shows larger specific surface area (78.19 m² g^-1) and open porosity (0.0187 cm³ g^-1). Electrochemically, A-HC exhibits a reversible capacity of 346.01 mAh g^-1 alongside an initial Coulombic efficiency of 88.51%, outperforming S-HC (275.67 mAh g^-1, 79.97%). Combined with multidimensional in situ characterizations, the sodium storage mechanism follows an adsorption-intercalation/pore filling model. This work establishes a clear structure property relationship linking precursor molecular topology to hard carbon performance, offering new insights for the rational design of biomass-derived hard carbon anodes.

Hard carbon is the most commercially viable anode for sodium-ion batteries, with low operating potential, high reversible capacity, abundant raw materials and low manufacturing cost. However, its intrinsic structural disorder, characterized by randomly stacked turbostratic graphene layers, nanopores and amorphous regions, has sparked long-standing debates on fundamental sodium storage mechanisms, significantly impeding rational electrode design and industrial translation. This review overviews sodium storage processes in hard carbon, analyzes synergistic contributions of intercalation, pore filling and surface adsorption, and establishes microstructural-electrochemical performance correlations. It focuses on four mainstream modification strategies: Precursor engineering, pore structure regulation, heteroatom doping and interface engineering, elucidating their enhancement mechanisms and discussing inherent limitations and trade-offs. Finally, it outlines key challenges and future directions, providing critical theoretical and technical guidance for next-generation hard carbon anodes and practical sodium-ion battery deployment.

LiFePO₄ is widely used as a stable and environmentally benign cathode material. However, its reuse potential is constrained by recycling challenges and significant performance degradation after decommissioning. Therefore, how to effectively improve the electrochemical performance of regenerated LiFePO₄ materials and enhance their stability during cycling has become the focus of current research. In this research, Sm doping was introduced to optimize regenerated LiFePO₄ cathode materials via a plasma ball milling assisted solid-state calcination method. Comparison between spent LiFePO₄ and Sm-doped regenerated cathodes revealed that the appropriate level of Sm doping effectively maintained the crystal structure of LiFePO₄. It also promoted a more uniform particle morphology and a reduced particle size, which is beneficial for shortening Li⁺ transport pathways. This enhancement significantly improved electronic conductivity, leading to enhanced electrochemical performance. The 2% Sm doped regenerated material exhibited optimal performance, achieving an initial charge-discharge specific capacity of 142.2 mAh·g^–1 at 1 C and maintaining a capacity retention of 96.5% after 200 cycles. This conclusion is of significant importance for improving resource utilization efficiency of spent LiFePO₄ batteries.

The development of sodium-ion battery technology has played a pivotal role in driving innovation within the energy storage field. Over the past several years, ranging from laboratories to industrial practice, this field has achieved phased results. However, current sodium-ion battery systems are hard-pressed to meet the increasingly stringent demands of the market for high energy density, long cycle life, and rapid charging and discharging. In recent years, hard carbon anodes have attracted the attention of numerous researchers due to their unique structural characteristics and sodium-storage potential. This review systematically and comprehensively examines the working principles and compositions of sodium-ion battery, critically evaluates common anode materials, and analyzes the sodium storage mechanism in hard carbon. Moreover, this review comprehensively summarizes multi-dimensional performance improvement strategies, such as morphology engineering, heteroatom functionalization, defect engineering, and electrolyte optimization, and deeply explores future development directions of sodium-ion batteries and hard carbon anode, offering more valuable insights and a solid theoretical foundation for promoting the development of hard carbon anode technology and accelerating the commercialization process of sodium-ion battery.

Lithium-oxygen (Li-O₂) battery is notable for the high theoretical energy density, and its widespread adoption has the potential to fundamentally transform the energy consumption landscape. However, the development of Li-O₂ batteries has been hindered by issues such as slow reaction kinetics, high overpotential, and unstable cycle life. Rational design of cathode materials has emerged as an effective strategy for addressing these challenges. Biomass, a renewable resource, holds significant importance in the fabrication of derived carbon cathode with exceptional performance; this efficacy is largely due to its intrinsic pore structure and the presence of heteroatoms, representing a significant advancement in the field. This review outlines optimization strategies for biomass-derived carbon cathode based on the reaction mechanism of Li-O₂ batteries. It introduces cross-scale characterization methods to analyze the properties of the carbon materials and explores the theoretical underpinnings of functional atom doping as a means to enhance electrochemical performance. Recent advancements in utilizing biomass-derived carbon as a porous cathode for Li-O₂ batteries are assessed, highlighting the relationship between microstructural development and performance variations. Furthermore, a succinct overview of the challenges faced by biomass-derived carbon-based Li-O₂ batteries is provided, along with proposed perspectives on the direction of development. This work seeks to improve the stability and catalytic efficiency of biomass-derived carbon cathode, ultimately aiming to facilitate the broader commercial application of Li-O₂ battery technology.